Warfarin Overdose Management Flashcards
Typical dose of warfarin
10mg if frail 5mg as a starting dose
Subsequent doses depends on prothrombin time reported as an INR
Where an immediate effect if required such as in DVT or PE heparin or LMWH is given concurrently in secondary care
Warfarin used in caution in following groups of people
Elderyly
Peptic ulcer , gi bleed ,
Uncontrolled HTN
NSAID or steroid use
Thyroid disorders as rate of warfarin metabolism depends on thyroid status
What drugs enhance warfarin effect
Binge drinking
Amiodarone
Co-tri, macrolides
SSRI, TCA - offer traazodone instead
Aspirin
Fluconazole
Cranberry juice
Clopidogrel
Steroids
Vibrates
Glucosamine
NSAIDs
Tamoxifen
Thyroxine
What drugs enhance warfarin effect
Binge drinking
Amiodarone
Co-tri, macrolides
SSRI, TCA - offer traazodone instead
Aspirin
Fluconazole
Cranberry juice
Clopidogrel
Steroids
Vibrates
Glucosamine
NSAIDs
Tamoxifen
Thyroxine
What drugs reduce effect of warfarin so need to increase warfarin dose
St John wort
Rifampucin
Carbamazepine
Phenobarbital
Phenytoin
Vit k complexes such as green veg
If risk of severe bleeding how long before surgery should you stop wafarin
3-5 days - use heparin up till day of instead
What is considered a good target value of warfarin considered satisfactory
An INR that is within 0.5 units of the target value
Common problems that require INR of 2.5
DVT
PE
AF
MITRAL STMEOSIS OR REGURGITATION
Major bleeding - fatal bleeding, sx in critical area such as brain, pericardium and significant hb drop what do you do with warfarin
Stop warfarin and IV Vit k 1 ( phytomenadione)
And prothrombin complex concentrate (factors 2, 7, 9, 10)
What is included in prothrombin complex concentrate (factors 2, 7, 9, 10)
(factors 2, 7, 9, 10)
INR over 8 with minor bleeding
Stop warfarin and give phytomenadione by slow IV inj
Dose can be repeated after 24hr if still to high
Greater than 8 with no bleeding
Stop warfarin and give phytomenadione by mouth
Restart warfarin when the INR is less than 5
INR between 5-8 with minor bleeding
Stop warfarin and give phytomandione by slow IV injection
Between 5-8 with no bleeding
Withhold 1 or 2 doses of warfarin and reduce subsequent maintenance dose
What advice should I give to a person receiving wafarin?
Yellow book ( contains alert card) and get INR checked regularly
Take warfarin same time each day, inform staff it taken too much or missed
Never take a double dose if missed just continue usually regime
Seek advice before changing diet
Limit alcohol i take max two days
Any bleeding, back pain or difficulty bleeding
